Medical electrical lead

ABSTRACT

A medical device lead. The lead includes one or more jacketed conductive elements. The jacket comprises one or more covers. A first cover of polytetrafluoroethylene (PTFE) is in direct contact with the at least one conductive element. The at least one conductive element and the PTFE cover are coiled. The coiled conductive element can substantially retain its original coiled shape.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority and other benefits from U.S.Provisional Patent Application Ser. No. 60/973,479 filed Sep. 19, 2007,incorporated herein by reference in its entirety. The presentapplication also claims priority and other benefits from U.S.Provisional Patent Application Ser. No. 60/972,114 filed Sep. 13, 2007,incorporated herein by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to implantable medical devices and, moreparticularly, to implantable medical leads.

BACKGROUND

The human anatomy includes many types of tissues that can eithervoluntarily or involuntarily, perform certain functions. After disease,injury, or natural defects, certain tissues may no longer operate withingeneral anatomical norms. For example, after disease, injury, time, orcombinations thereof, the heart muscle may begin to experience certainfailures or deficiencies. Certain failures or deficiencies can becorrected or treated with implantable medical devices (IMDs), such asimplantable pacemakers, implantable cardioverter defibrillator (ICD)devices, cardiac resynchronization therapy defibrillator devices, orcombinations thereof.

IMDs detect and deliver therapy for a variety of medical conditions inpatients. IMDs include implantable pulse generators (IPGs) orimplantable cardioverter-defibrillators (ICDs) that deliver electricalstimuli to tissue of a patient. ICDs typically comprise, inter alia, acontrol module, a capacitor, and a battery that are housed in ahermetically sealed container with a lead extending therefrom. It isgenerally known that the hermetically sealed container can be implantedin a selected portion of the anatomical structure, such as in a chest orabdominal wall, and the lead can be inserted through various venousportions so that the tip portion can be positioned at the selectedposition near or in the muscle group. When therapy is required by apatient, the control module signals the battery to charge the capacitor,which in turn discharges electrical stimuli to tissue of a patientthrough via electrodes disposed on the lead, e.g., typically near thedistal end of the lead. Typically, a medical electrical lead includes aflexible elongated body with one or more insulated elongated conductors.Each conductor electrically couples a sensing and/or a stimulationelectrode of the lead to the control module through a connector module.It is desirable to develop implantable medical electrical leads with newlead body subassemblies.

BRIEF DESCRIPTION OF DRAWINGS

Aspects and features of the present invention will be appreciated as thesame becomes better understood by reference to the following detaileddescription of the embodiments of the invention when considered inconnection with the accompanying drawings, wherein:

FIG. 1 is a conceptual schematic view of an implantable medical devicein which a medical electrical lead extends therefrom;

FIG. 2 is a schematic view of a medical electrical lead;

FIG. 3A is a schematic view of a distal end of the medical electricallead;

FIG. 3B is a cross-sectional view taken along plane A-A of the distalend of the medical electrical lead depicted in FIG. 3A;

FIG. 4A is a schematic view of a jacket that surrounds one or moreconductive elements in a medical electrical lead;

FIG. 4B is a schematic sectional view of the jacket depicted in FIG. 4A;

FIG. 5A is a schematic view of an exemplary insulated conductiveelement;

FIG. 5B is a cross-sectional view of the insulated conductive elementdepicted in FIG. 5A;

FIG. 6A is a schematic view of an exemplary insulated multi-conductorelement;

FIG. 6B is a schematic cross-sectional view of an exemplary insulatedmulti-conductor element depicted in FIG. 6A;

FIG. 7A is a schematic view of another exemplary insulatedmulti-conductor element;

FIG. 7B is a schematic cross-sectional view of an exemplary insulatedmulti-conductor element depicted in FIG. 7A;

FIG. 8A is a schematic view of an exemplary insulated multi-conductorelement before its stretched;

FIG. 8B is a schematic view of an exemplary insulated multi-conductorelement being stretched;

FIG. 8C is an exemplary insulated multi-conductor element in a relaxedposition and returning to its original coiled shape;

FIG. 9 is a schematic view of an exemplary insulated multi-conductorelement wrapped around a tubular insulative element or a coil liner;

FIG. 10A is a schematic view of yet another exemplary insulatedmulti-conductor element wrapped around a mandrel;

FIG. 10B is a cross-sectional view of the insulated conductive elementdepicted in FIG. 10A; and

FIG. 11 is a flow diagram for forming a coiled jacketed conductiveelement.

DETAILED DESCRIPTION

The present disclosure relates to a medical electrical lead thatincludes a lead body. The lead body comprises at least one elongatedconductive element, such as a cable, surrounded by an elongated jacket.The jacket can include one or more covers. The jacket can be formedthrough an extrusion process directly over the conductive element, whichreduces or eliminates diametrical expansion of the coiled conductiveelement which can occur due to elastic “springback” or stress relaxationof the coiled composite structure. A first cover comprisesethylene-tetraflouroethylene (ETFE) extruded directly over theconductive element. In one embodiment, the conductive element and thejacket, is then formed into a coil.

In one embodiment, the PEEK undergoes a molecular mobility process priorto or during introduction of the ETFE over an elongated conductiveelement. Exemplary molecular mobility processes can include thermalannealing, stress relieving, or other suitable means for a material toachieve a more flexible molecular structure.

Thermal processing can involve exposing the composite structure to acontrolled heating and cooling schedule. Suitable temperatures candepend upon the type of polymeric material and/or number of covers orlayer(s) employed, to form a jacket, a composite jacket, or one or morelongitudinal elements that can house conductive elements. ETFE, forexample, can be thermally processed at about 130-200 degrees Celsius (°C.). Thermal processing of ETFE onto an elongated conductive elementcauses the conductive element to substantially maintain a controlledpitch and diameter after coiling. For example, a conductive element suchas a cable in a coil shape can substantially maintain up to about 99percent of its original coil shape, after the conductive element hasbeen released from, for example, a mandrel which is after a thermalprocessing has been performed. The final diameter and pitch of a coilshape is generally based upon the coil composite structure and itselastic “springback” or coil expansion from stress relaxation, thewinding diameter/pitch, and the processing parameters used to set thecoil shape. In one embodiment, a coiled cable is more resistant to flexfatigue compared to a linear or straight cable. Additionally, smallercoiled cable diameters are achieved through application of theprinciples described herein. In one embodiment, about 10 percent or moreof a diameter reduction in the coiled conductive element is achievedthrough the principles described herein. In another embodiment, about 5percent or more diameter reduction is achieved in the coiled conductiveelement through the principles described herein. In still yet anotherembodiment, about 2 percent or more diameter reduction is achieved inthe coiled conductive element through the principles described herein.Smaller coiled cable diameters allow for smaller sized leads to beproduced. Smaller sized leads can include 7 French or smaller. Inanother embodiment, smaller sized leads can include 6 French or smaller.In still yet another embodiment, smaller sized leads can include 5French or smaller.

The principles described herein are applicable to all types of medicalelectrical leads. For example, the disclosure applies to cardiovascularleads (e.g. high voltage leads, low voltage leads etc.), neurologicalleads, or other suitable applications.

FIG. 1 depicts a medical device system 100. A medical device system 100includes a medical device housing 102 having a connector module 104(e.g. international standard (IS)-1, defibrillation (DF)-1, IS-4 etc.)that electrically couples various internal electrical components housedin medical device housing 102 to a proximal end 105 of a medicalelectrical lead 106. A medical device system 100 may comprise any of awide variety of medical devices that include one or more medical lead(s)106 and circuitry coupled to the medical electrical lead(s) 106. Anexemplary medical device system 100 can take the form of an implantablecardiac pacemaker, an implantable cardioverter, an implantabledefibrillator, an implantable cardiacpacemaker-cardioverter-defibrillator (PCD), a neurostimulator, a tissueand/or muscle stimulator. IMDs are implanted in a patient in anappropriate location. Exemplary IMDs are commercially available asincluding one generally known to those skilled in the art, such as theMedtronic CONCERTO™, SENSIA™, VIRTUOSO™, RESTORE™, RESTORE ULTRA™, soldby Medtronic, Inc. of Minnesota. Non-implantable medical devices orother types of devices may also utilize batteries such as external drugpumps, hearing aids and patient monitoring devices or other suitabledevices. Medical device system 100 may deliver, for example, pacing,cardioversion or defibrillation pulses to a patient via electrodes 108disposed on distal end 107 of one or more lead(s) 106. Specifically,lead 106 may position one or more electrodes 108 with respect to variouscardiac locations so that medical device system 100 can deliverelectrical stimuli to the appropriate locations.

FIG. 2 depicts lead 106. Lead 106 includes a lead body 117 that extendsfrom proximal end 105 to a distal end 107. Lead body 117 can include oneor more connectors 101, and one or more jacketed conductive elements 112a-d. A jacket (also referred to as a liner, longitudinal element,coating) extends along and longitudinally around the conductive elements112 a-d and can serve to contain or mechanically constrain one or moreconductive elements 112 a-d. A jacket can also insulate one or moreconductive elements 112 a-d. Connector module 104 can contain connectors122, such as set screws, serve to electrically and mechanically connectconductive elements 112 a-d to ports (not shown) of connector module104. Conductive element 112 c (also referred to as a “conductor coil,”“torque coil”, “distal tip conductor”) can extend to the distal end 107and can optionally be coupled to a retractable and/or extendable helicaltip. One or more conductive elements 112 a,b serve as, or are connectedto, defibrillation coils 103 a,b that deliver electrical stimuli, whennecessary, to tissue of a patient. Lead 106 can also include aconductive element 112 d that extends from the proximal end 105 to ringelectrode 118 while another conductive element 112 c extends fromproximal end 105 to tip electrode 120.

Electrically conductive elements 112 a-d can include coils, wires, coilwound around a filament, cables, conductors or other suitable members.Conductive elements 112 a-d can comprise platinum, platinum alloys,titanium, titanium alloys, tantalum, tantalum alloys, cobalt alloys(e.g. MP35N, a nickel-cobalt alloy etc.), copper alloys, silver alloys,gold, silver, stainless steel, magnesium-nickel alloys, palladium,palladium alloys or other suitable materials. Electrically conductiveelement 112 a-d is covered, or substantially covered, longitudinallywith a jacket 130 (also referred to as a liner, a longitudinal element,a longitudinal member, a coating, a tubular element, a tube or acylindrical element). In yet another embodiment, each conductive element112 a-d is surrounded by a tubular element, which can possess a circularor a non-circular cross-section. An outercover or outerjacket in a leadbody 117 can exhibit a non-circular cross-section.

Typically, the outer surface of electrodes 108 such as the ringelectrode 118, the tip electrode 120, and the defibrillation coils 103a,b are exposed or not covered by a jacket 130 or liner so thatelectrodes 108 can sense and/or deliver electrical stimuli to tissue ofa patient. A sharpened distal tip (not shown) of tip electrode 120facilitates fixation of the distal end of helically shaped tip electrode120 into tissue of a patient.

Referring to FIGS. 3A-3B, and 4A-4B, lead body 117 can include one ormore jackets 130 and one or more conductive elements 112 a,b,d. In oneembodiment, lead body 117 comprises one or more jackets 130 disposed inanother jacket 130. In still yet another embodiment, lead body 117comprises one or more jackets 130 with an outer cover 140 that surroundsthe one or more jackets 130.

Each jacket 130 can include one or more covers, as depicted in FIGS.4A-4B with cross-sectional segment 128. Each cover 146, 148, 150, and152 can comprise one or more layers of polymeric compounds. Numerousembodiments of jacket 130 or liner are summarized in Table 1 anddescribed in greater detail below. The first embodiment listed in Table1 involves a single cover or first cover 144 of PEEK such that the innerlumen of first cover 144 is adjacent to a conductive element 112 a,b,d,a delivery device (not shown) such as a guide wire or stylet, or a lumenwithout a delivery device, or a conductive element 112 c such as aconductor coil. PEEK is commercially available as Optima from Invibiolocated in Lancashire, United Kingdom. The first cover 144 of PEEK canbe formed in a variety of ways. In one embodiment, the single cover orfirst cover of PEEK may be introduced or applied directly over aconductive element 112 a-d through extrusion. Extrusion is the processof forming a continuous shape by applying force to a material through adie. Polymer extrusion is described, for example, in Chris Rauwendaal,pp. 1-30, 155-205, Polymer Extrusion (4^(th) ed. 2001), which isincorporated by reference in relevant part. Generally, the polymericmaterial is heated in a barrel of the extruder until it attains orexceeds its melt temperature. Thereafter, the polymeric material issimultaneously extruded through a die of the extruder over theconductive element 112 a-d while the conductive element 112 a-dcontinues to move away from the extruder and/or the conductive element112 a-d moves radially. The polymeric material then forms into a firstcover 144 (also referred to as first longitudinal element) over theconductive element 112 a-d. After formation of first cover 144, thepolymeric material is allowed to cool. There are numerous ways to coolthe polymeric material. For example, the first cover 144 can be aircooled, which is a slow cooling process. Alternatively, the first cover144 can be placed in a cool water bath. In yet another embodiment, thefirst cover 144 and the conductive element 112 a-d can be placed into acooler such as a refrigeration unit to quickly cool the polymericmaterial. The process of extruding polymeric material and allowing thepolymeric material applies to each embodiment listed below.

The cover of PEEK can have a thickness of about 0.0005 inches to about0.0015 inches. In another embodiment, the cover of extruded PEEK canpossess a thickness that ranges from about 0.00020 inches to about0.0012 inches. In yet another embodiment, the cover of PEEK has athickness of about 0.0005 inches to about 0.0020 inches. The PEEK incombination with the conductive element 112 a-d forms a compositestructure.

The composite structure is then formed into a coil shape. In oneembodiment, the composite structure is formed into a coil through, forexample, winding the conductive element 112 a,b,d over a mandrel 702, acylindrically shaped element, exemplarily depicted in FIG. 10A. Inparticular, the mandrel 702 can be a high tensile strength wire that isheld under tension (i.e. both ends of the mandrel 702 are clamped) whilethe filars of the coil are wound around the diameter of the mandrel 702.While the mandrel 702 continues to rotate or move radially, filars ofthe coil are being wound or served around mandrel 702. The filars aresimultaneously translated along mandrel 702 while being wound aboutmandrel 702. An exemplary amount of winding tension applied is about 15grams; however, it is appreciated that other amounts of winding tensionscan be used The amount of tension used can depend upon the geometryand/or the mechanical characteristics (e.g. break load or strength ofthe cable filars, yield strength of the cable filars, etc.) of the cablefilars that are to be formed. Coil winding equipment is commerciallyavailable from Accuwinder Engineering Company located in San Dimas,Calif.

The coiled conductive element 112 a,b,d can be mechanically constrainedto minimize or eliminate diametrical and/or axial expansion of thecoiled conductive element 112 a,b,d. Exemplary methods for mechanicallyconstraining the conductive element 112 a,b,d can include clamping orbonding the proximal and distal ends of 112 a,b,d to a mandrel 702 orother suitable fixture or component. The clamp(s) or clamp mechanism(s)can mechanically constrain or secure the coiled conductive element 112a,b,d against the mandrel 702, as depicted, for example, in FIG. 10 suchthat coiled conductive element 112 a,b,d will not rotate or expanddiametrically and/or axially. Exemplary clamping mechanisms can take theform of a mechanical clamp, toggle(s) or heat shrink tubing(s). Theclamping mechanism can mechanically constrain the coil conductiveelement on the mandrel and hold the coiled conductive element in placeduring subsequent operations.

In one embodiment, after the extrusion coating process and the coilingprocess, no thermal processing is performed on the coiled conductiveelement 112 a,b,d. In another embodiment, after the extrusion coatingprocess and the coiling process, thermal processing is performed on thecoiled conductive element 112 a,b,d. In still yet another embodiment,after the extrusion coating process, thermal processing is performed onthe conductive element 112 a,b,d which is thereafter followed by acoiling process to coil the conductive element 112 a,b,d. In yet anotherembodiment, after the extrusion coating process, the coiled conductiveelement 112 a,b,d is thermal processed and can then undergo a coilingprocess. After coiling process, the coiled conductive element 112 a,b,dundergoes a second thermal process.

The composite structure can then undergo a thermal process; however, itis appreciated that a thermal process may be unnecessary to form, forexample, a coiled cable assembly. In one embodiment, the compositestructure is placed or run through a chamber. For example, a chamber oroven, commercially available from Despatch Industries, Minneapolis,Minn., can be used to process the composite structure. In oneembodiment, the temperature in the chamber is about 130° C. to about210° C. In one embodiment, the temperature in the chamber is about 130°C. to about 210° C. The composite structure remains at this temperaturefor about 30 seconds to about 45 minutes and then is cooled to form theETFE polymeric material and conductive element 112 a,b,d in its coiledshape. The mechanical constraint is then removed such as throughde-clamping or cutting the proximal and distal ends of the conductiveelement 112 from the mandrel.

The first embodiment listed in Table 1 relates to a jacket 130 formed ofa first cover 144. First cover 144 of ethylene-tetrafluoroethylene(ETFE) can possess a thickness that ranges from about 0.0005 inches toabout 0.0015 inches of extruded ETFE. In another embodiment, first cover144 can possess a thickness that ranges from about 0.00020 inches toabout 0.003 inches. A composite structure is composed of the first cover144 over the conductive element 112 a,b,d. The composite structure isformed into a coil shape and then mechanically constrained, aspreviously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The second embodiment listed in Table 1 relates to a jacket 130 formedof a first, and second covers 144, 146. First cover 144 of ETFE canpossess a thickness that ranges from about 0.0005 inches to about 0.0015inches of extruded ETFE. In another embodiment, first cover 144 canpossess a thickness that ranges from about 0.00020 inches to about 0.003inches. In another embodiment, first cover 144 can possess a thicknessthat ranges from about 0.00020 inches to about 0.001 inches. First cover144 of ETFE is formed by extruding the ETFE over a conductive element112 a,b,d. After the first cover 144 of ETFE has been formed, a secondcover 146 of ETFE is introduced over the first cover 144. Second cover146 can possess a thickness that ranges from about 0.00020 inches toabout 0.001 inches. A composite structure is composed of the first, andsecond covers 144, 146 respectively, over the conductive element 112a,b,d. The composite structure is formed into a coil shape and thenmechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The third embodiment listed in Table 1 relates to a jacket 130 formed ofa first, second and third covers 144, 146, 148. First cover 144 of ETFEcan possess a thickness that ranges from about 0.0005 inches to about0.0015 inches of extruded ETFE. In another embodiment, first cover 144can possess a thickness that ranges from about 0.00020 inches to about0.001 inches. First cover 144 of ETFE is formed by extruding the ETFEover a conductive element 112 a,b,d. After the first cover 144 of ETFEhas been formed, a second cover 146 of ETFE is introduced over the firstcover 144. Second cover 146 can possess a thickness that ranges fromabout 0.00020 inches to about 0.001 inches. A third cover 148 of ETFE isintroduced over the second cover 146 in which the third cover 148 canpossess a thickness that ranges from about 0.00020 inches to about 0.001inches. A composite structure is composed of the first, second, andthird covers 144, 146, 148 respectively, over the conductive element 112a,b,d. The composite structure is formed into a coil shape and thenmechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The fourth embodiment listed in Table 1 involves a first cover 144 ofETFE followed by a second cover 146 of fluorinated ethylene propylene(FEP). First cover 144 of ETFE can possess a thickness that ranges fromabout 0.0005 inches to about 0.0015 inches of extruded ETFE. In anotherembodiment, first cover 144 can possess a thickness that ranges fromabout 0.00020 inches to about 0.001 inches. After the first cover 144 ofETFE has been formed, a second cover 146 of FEP is introduced over thefirst cover 144. Second cover 146 can possess a thickness that rangesfrom about 0.00020 inches to about 0.001 inches. In another embodiment,second cover 146 can possess a thickness that ranges from about 0.00020inches to about 0.003 inches. The composite structure, comprised of thefirst and second covers 144, 146 over the conductive element 112 a,b,d,is formed into a coil shape and then mechanically constrained.

Thereafter, the composite structure undergoes thermal annealing orstress relieving in a chamber, as previously described. The temperatureof the chamber is about 130° C. to about 210° C. for about 30 seconds toabout 30 minutes to allow the polymeric material to form jacket 130 overconductive element 112 a,b,d, after which time the mechanical constraintis removed.

The fifth embodiment listed in Table 1 relates to a jacket 130 formed ofa first, second and third covers 144, 146, 148. First cover 144 of ETFEcan possess a thickness that ranges from about 0.0005 inches to about0.0015 inches of extruded ETFE. In another embodiment, first cover 144can possess a thickness that ranges from about 0.00020 inches to about0.001 inches. First cover 144 of ETFE is formed by extruding the ETFEover a conductive element 112 a,b,d. After the first cover 144 of ETFEhas been formed, a second cover 146 of ETFE is introduced over the firstcover 144. Second cover 146 can possess a thickness that ranges fromabout 0.00020 inches to about 0.001 inches. A third cover 148 of FEP isintroduced over the second cover 146 in which the third cover 148 canpossess a thickness that ranges from about 0.00020 inches to about 0.001inches. A composite structure is composed of the first, second, andthird covers 144, 146, 148 respectively, over the conductive element 112a,b,d. The composite structure is formed into a coil shape and thenmechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The sixth embodiment listed in Table 1 involves a first cover 144 ofETFE followed by a second cover 146 of FEP. First cover 144 of ETFE canpossess a thickness that ranges from about 0.0005 inches to about 0.0015inches of extruded ETFE. In another embodiment, first cover 144 canpossess a thickness that ranges from about 0.00020 inches to about 0.001inches. After the first cover 144 of ETFE has been formed, a secondcover 146 of perfluoroalkoxy (PFA) is introduced over the first cover144. Second cover 146 can possess a thickness that ranges from about0.00020 inches to about 0.001 inches. In another embodiment, secondcover 146 can possess a thickness that ranges from about 0.00020 inchesto about 0.003 inches. The composite structure, comprised of the firstand second covers 144, 146 over the conductive element 112 a,b,d, isformed into a coil shape and then mechanically constrained.

Thereafter, the composite structure undergoes thermal annealing orstress relieving in a chamber, as previously described. The temperatureof the chamber is about 130° C. to about 210° C. for about 30 seconds toabout 30 minutes to allow the polymeric material to form jacket 130 overconductive element 112 a,b,d, after which time the mechanical constraintis removed.

The seventh embodiment listed in Table 1 relates to a jacket 130 formedof a first, second and third covers 144, 146, 148. First cover 144 ofETFE can possess a thickness that ranges from about 0.0005 inches toabout 0.0015 inches of extruded ETFE. In another embodiment, first cover144 can possess a thickness that ranges from about 0.00020 inches toabout 0.001 inches. First cover 144 of ETFE is formed by extruding theETFE over a conductive element 112 a,b,d. After the first cover 144 ofETFE has been formed, a second cover 146 of ETFE is introduced over thefirst cover 144. Second cover 146 can possess a thickness that rangesfrom about 0.00020 inches to about 0.001 inches. A third cover 148 ofPFA is introduced over the second cover 146 in which the third cover 148can possess a thickness that ranges from about 0.00020 inches to about0.001 inches. A composite structure is composed of the first, second,and third covers 144, 146, 148 respectively, over the conductive element112 a,b,d. The composite structure is formed into a coil shape and thenmechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The eighth embodiment listed in Table 1 relates to a jacket 130 formedof a first cover 144. First cover 144 of polyflourotetraethylene (PTFE)such as PTFE (extruded and nonporous) can possess a thickness thatranges from about 0.0005 inches to about 0.0015 inches of extruded ETFE.In another embodiment, first cover 144 can possess a thickness thatranges from about 0.00020 inches to about 0.003 inches. A compositestructure is composed of the first cover 144 over the conductive element112 a,b,d. The composite structure is formed into a coil shape and thenmechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The ninth embodiment listed in Table 1 relates to a jacket 130 formed ofa first, and second covers 144, 146. First cover 144 of PTFE (extrudedand nonporous) can possess a thickness that ranges from about 0.0005inches to about 0.0015 inches of extruded PTFE (extruded and nonporous).Unlike other polymers, PTFE is not melt-processable. Fully dense ornon-porous PTFE can be produced via a “paste extrusion” process. Withthis process a very fine PTFE resin is mixed with a hydrocarbonextrusion aid (e.g. mineral spirits etc.) and compressed to form abillet called a preform, which is “ram extruded” at high pressures. Theresulting extruded form is then thermally treated to remove theextrusion aid and sinter the fine particles of PTFE together.

In another embodiment, first cover 144 can possess a thickness thatranges from about 0.00020 inches to about 0.003 inches. In anotherembodiment, first cover 144 can possess a thickness that ranges fromabout 0.00020 inches to about 0.001 inches. First cover 144 of PTFE(extruded and nonporous) is formed by extruding the PTFE (extruded andnonporous) over a conductive element 112 a,b,d. After the first cover144 of PTFE (extruded and nonporous) has been formed, a second cover 146of PTFE (extruded and nonporous) is introduced over the first cover 144.Second cover 146 can possess a thickness that ranges from about 0.00020inches to about 0.001 inches. A composite structure is composed of thefirst, and second covers 144, 146 respectively, over the conductiveelement 112 a,b,d. The composite structure is formed into a coil shapeand then mechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The tenth embodiment listed in Table 1 relates to a jacket 130 formed ofa first, second and third covers 144, 146, 148. First cover 144 of PTFE(extruded and nonporous) can possess a thickness that ranges from about0.0005 inches to about 0.0015 inches of PTFE (extruded and nonporous).In another embodiment, first cover 144 can possess a thickness thatranges from about 0.00020 inches to about 0.001 inches. First cover 144of PTFE (extruded and nonporous) is formed by extruding the PTFE(extruded and nonporous) over a conductive element 112 a,b,d. After thefirst cover 144 of PTFE (extruded and nonporous) has been formed, asecond cover 146 of PTFE (extruded and nonporous) is introduced over thefirst cover 144. Second cover 146 can possess a thickness that rangesfrom about 0.00020 inches to about 0.001 inches. A third cover 148 offluorinated ethylene propylene (FEP) is introduced over the second cover146 in which the third cover 148 can possess a thickness that rangesfrom about 0.00020 inches to about 0.001 inches. A composite structureis composed of the first, second, and third covers 144, 146, 148respectively, over the conductive element 112 a,b,d. The compositestructure is formed into a coil shape and then mechanically constrained,as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The eleventh embodiment listed in Table 1 relates to a jacket 130 formedof a first, second and third covers 144, 146, 148. First cover 144 ofPTFE (extruded and nonporous) can possess a thickness that ranges fromabout 0.0005 inches to about 0.0015 inches of PTFE (extruded andnonporous). In another embodiment, first cover 144 can possess athickness that ranges from about 0.00020 inches to about 0.001 inches.First cover 144 of PTFE (extruded and nonporous) is formed by extrudingthe PTFE (extruded and nonporous) over a conductive element 112 a,b,d.After the first cover 144 of PTFE (extruded and nonporous) has beenformed, a second cover 146 of PTFE (extruded and nonporous) isintroduced over the first cover 144. Second cover 146 can possess athickness that ranges from about 0.00020 inches to about 0.001 inches. Athird cover 148 of PFA is introduced over the second cover 146 in whichthe third cover 148 can possess a thickness that ranges from about0.00020 inches to about 0.001 inches. A composite structure is composedof the first, second, and third covers 144, 146, 148 respectively, overthe conductive element 112 a,b,d. The composite structure is formed intoa coil shape and then mechanically constrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

The tenth embodiment listed in Table 1 relates to a jacket 130 formed ofa first, second and third covers 144, 146, 148. First cover 144 of PTFE(extruded and nonporous) can possess a thickness that ranges from about0.0005 inches to about 0.0015 inches of PTFE (extruded and nonporous).In another embodiment, first cover 144 can possess a thickness thatranges from about 0.00020 inches to about 0.001 inches. First cover 144of PTFE (extruded and nonporous) is formed by extruding the PTFE(extruded and nonporous) over a conductive element 112 a,b,d. After thefirst cover 144 of PTFE (extruded and nonporous) has been formed, asecond cover 146 of PTFE (extruded and nonporous) is introduced over thefirst cover 144. Second cover 146 can possess a thickness that rangesfrom about 0.00020 inches to about 0.001 inches. A third cover 148 ofethylene-tetraflouroethylene based copolymer (EFEP) is introduced overthe second cover 146 in which the third cover 148 can possess athickness that ranges from about 0.00020 inches to about 0.001 inches. Acomposite structure is composed of the first, second, and third covers144, 146, 148 respectively, over the conductive element 112 a,b,d. Thecomposite structure is formed into a coil shape and then mechanicallyconstrained, as previously described.

The composite structure then undergoes thermal annealing or stressrelieving in a chamber. The temperature in the chamber is about 130° C.to about 210° C. for about 30 seconds to about 30 minutes to allow thepolymeric material to form jacket 130 around conductive element 112a,b,d. Thereafter, the mechanical constraint is removed.

Table 1, presented below, summarizes the various embodiments of jacket130.

TABLE 1 Embodiments of jacket 130 that comprise one or more polymericcompounds No. First Cover Second Cover Third Cover N Cover 1 ETFE 2 ETFEETFE 3 ETFE ETFE ETFE 4 ETFE FEP 5 ETFE ETFE FEP 6 ETFE PFA 7 ETFE ETFEPFA 8 PTFE (extruded, nonporous) 9 PTFE PTFE (extruded, (extruded,nonporous) nonporous) 10 PTFE PTFE (extruded, FEP (extruded, nonporous)nonporous) 11 PTFE PTFE (extruded, PFA (extruded, nonporous) nonporous)12 PTFE PTFE (extruded, EFEP (extruded, nonporous) nonporous)

The insulated conductive element formed through jacket 130 overconductive element 112 a,b,d can be helically wrapped around a mandrel(not shown). After winding the insulated cable onto the mandrel andmechanically restraining this composite structure, the polymericmaterial over the conductive element (e.g. cable etc.) can be annealedto minimize springback and allow the conductive element (e.g. cableetc.) to retain its coiled shape. After being removed from the mandrel,the conductive element (e.g. cable etc.) retains its coiled shape.

Insulated conductive element 200 is depicted in FIGS. 5A-5B. Insulatedconductive element 200 includes a conductive element 112 a,b,d (i.e.cable, coiled cable etc.) with a thin polymeric material 204 or coverthat has been thermally processed (e.g. annealed etc.) to conductiveelement 112 a,b,d. Polymeric material 204 comprises a first and secondcovers 124 a, 124 b. Conductive element 112 a,b,d has an outer diameterof about 0.09 inches or less. In one embodiment, conductive element 112a,b,d can be a 1×19 cable construction with filaments composed ofMP35N/Ag core.

Referring to FIGS. 6A-6B, an insulated conductive element 300 isdepicted that comprises a set of conductors 302 a-c (i.e. threeconductors) and an insulative layer or cover 304. Conductive element 300such as a 1×19 cable MP35N/Ag core and has an outer diameter of about0.055 inches. Insulative layer 304 comprises a layer of PEEK and a layerof ETFE. In one embodiment, each layer of PEEK and ETFE is about 0.0008inches or less. In another embodiment, each layer of PEEK and ETFE isabout 0.002 inches or less.

Referring to FIG. 7A-7B, insulated conductive element 400 comprises aset of conductors 402 a-e (i.e. five conductors) and an insulative layeror cover 404. Conductive element 400 has an outer diameter of about0.060 inches and is a 1×19 cable. Insulative layer 404 comprises a layerof PEEK and a layer of ETFE. In one embodiment, each layer of PEEK andETFE is about 0.0008 inches or less. In another embodiment, each layerof PEEK and ETFE is about 0.002 inches or less.

Referring to FIGS. 8A-8C, jacketed conductive element 500 is shown asretaining its coiled shape despite being stretched. Conductive element500 comprises a 1×19 cable construction with filaments composed ofMP35N/Ag core with an insulative or jacketed layer, coating or cover.The insulative layer comprises a layer of PEEK and a layer of ETFE. Inone embodiment, each layer of PEEK and ETFE is about 0.0008 inches orless. In one embodiment, each layer of PEEK and ETFE is about 0.002inches or less. Referring to FIG. 8A, insulated conductive element 500is depicted in a relaxed position (FIG. 8A) over a mandrel. While overthe mandrel, conductive element 500 is thermally annealed. Referring toFIG. 8B, insulated conductive element 500 is depicted in a stretchedposition. Thereafter, insulated conductive element 500 moves to arelaxed position after being stretched (FIG. 8C). The insulatedconductive element 500 retains 99% or more of its original coiled shape.In another embodiment, insulated conductive element 500 comprises 95% ormore of its original coiled shape.

Referring to FIG. 9, insulated conductive element 600 is helicallywrapped around a coil liner 130. Insulated conductive element 600comprises a set of jacketed conductors 602 (i.e. five conductorscable-coil). Referring to FIG. 10A-10B, insulated conductive element 700is helically wrapped around a mandrel 702. Insulated conductive element700 comprises a set of conductors 702 (i.e. five conductors) and aninsulative layer or cover.

FIG. 11 is a flow diagram of an exemplary computer-implemented method ora manual process to form at least one cover of PEEK over the conductiveelement. At block 800, a counter, x, is initiated to 1 in order to countthe number polymer covers formed over a conductive element. At block810, a polymer is extruded (also referred to as introduced) over theconductive element. Polymers with high elastic modulus (i.e. stiffness)such as PEEK are preferred since PEEK can be annealed or stress relievedto increase crystallinity and set the coil shape in conductive element112 a-c. At block 820, the polymer cover can undergo an optional thermalprocess.

At block 830, the counter, X, is incremented by adding 1 to the previousvalue of X. At block 840, a determination is made as to whether asufficient number of polymer covers have been formed over the conductiveelement. In this embodiment, a determination is made as to whether X=Nwhere N equals the number of pre-selected covers to be added to theconductive element. If X does not equal N, the process control returnsto block 810 to extrude the same or different polymer over the previouspolymer cover. If x does equal N, then the process goes to block 850,where the jacketed conductive element undergoes coiling, as previouslydescribed. If x does not equal N, the process returns to introducinganother polymeric cover over the conductive element 112 a-d. If x doesequal N, no additional polymer covers are introduced over the conductiveelement 112 a-d. At block 850, the jacketed conductive element is formedinto a coil. At block 860, the coiled jacketed conductive element canundergo an optional thermal process. If the method is implemented on acomputer, the number of polymeric covers formed over the conductiveelement and/or the types of polymeric material used for each cover canbe displayed on a graphical user interface of a computer. Thecomputer-implemented instructions are executed on a processor of acomputer.

Co-pending U.S. patent application Ser. No. 12/211,093 entitled “MEDICALELECTRICAL LEAD” filed by Gregory A. Boser and Kevin R. Seifert andassigned to the same Assignee as the present invention. This co-pendingapplication is hereby incorporated herein by reference in its entirety.

Co-pending U.S. patent application Ser. No. 12/211,065 entitled “MEDICALELECTRICAL LEAD” filed by Gregory A. Boser and Kevin R. Seifert andassigned to the same Assignee as the present invention. This co-pendingapplication is hereby incorporated herein by reference in its entirety.

Co-pending U.S. patent application Ser. No. 12/211,092 entitled “MEDICALELECTRICAL LEAD” filed by Gregory A. Boser and Kevin R. Seifert andassigned to the same Assignee as the present invention. This co-pendingapplication is hereby incorporated herein by reference in its entirety.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

The invention claimed is:
 1. A medical electrical lead, comprising: Alead body that comprises a conductive element; wherein the conductiveelement is covered by a jacket and wherein the jacket comprises firstand second covers, the first cover being of extrudedpolytetrafluoroethylene (PTFE) directly contacting the conductiveelement and the second cover comprising one of PTFE,ethylene-tetrafluoroethylene (ETFE), ethylene-tetrafluorosthylene basedcopolymer (EFEP), perfluoroalkoxy (PFA) and fluorinated ethylenepropylene (FEP, and wherein the conductive element is a coiled, cabledconductor that after coiling has a diameter of up to 95% of a coileddiameter of the conductive element otherwise resulting from springbackafter coiling in the absence of the jacket.
 2. The medical electricallead of claim 1 further comprising a third cover comprising one of PTFE,ETFE, and EFEP.
 3. The medical electrical lead of claim 1 furthercomprising: a third cover of a polymeric material coupled to the firstcover, wherein the third cover comprises one of ETFE, PEP, PFA and EFEP.4. A medical electrical lead, comprising: A lead body that comprises aconductive element; wherein the conductive element comprises a multiplefilar cabled conductor and is covered by a jacket and wherein the jacketcomprises first and second covers, the first cover being of extrudedpolytetrafluoroethylene (PTFE) directly contacting the conductiveelement and the second cover comprising one of PTFE,ethylene-tetrafluoroethylene (ETFE), ethylene-tetrafluorosthylene basedcopolymer (EFEP), perfluoroalkoxy (PFA) and fluorinated ethylenepropylene (FEP, and wherein the conductive element is a coiled, cabledconductor that after coiling has a diameter of up to 95% of a coileddiameter of the conductive element otherwise resulting from springbackafter coiling in the absence of the jacket.
 5. The medical electricallead of claim 1 further comprising a third cover comprising one of PTFE,ETFE, and EFEP.
 6. The medical electrical lead of claim 1 furthercomprising: a third cover of a polymeric material coupled to the firstcover, wherein the third cover comprises one of ETFE, PEP, PFA and EFEP.